Extrasolar Planets

The search for Earth-like planets around late-type stars using ultra-stable spectrographs requires a very precise characterization of the stellar activity and the magnetic cycle of the star, since these phenomena induce radial velocity (RV) signals that can be misinterpreted as planetary signals.

Context. The existence of an extended neutral hydrogen exosphere around small planets can be used as an evidence for the presence of water in their lower atmosphere but, to date, such feature has not been securely detected in rocky exoplanets.

Every school kid knows that Earth has a magnetic field -- it's what makes compasses align north-south and lets us navigate the oceans. It also protects the atmosphere, and thus life, from the Sun's powerful wind.

The important role of stellar irradiation in envelope removal for planets with diameters of <2 R⊕ has been inferred both through theoretical work and the observed bimodal distribution of small planet occurrence as a function of radius.

A low-amplitude periodic signal in the radial-velocity (RV) time-series of Barnard's Star was recently attributed to a planetary companion with a minimum mass of ∼3.2 M⊕ at an orbital period of ∼233 days.

Exoplanet interior modelling usually makes the assumption that the elemental abundances of a planet are identical to those of its host star. Host stellar abundances are good proxies of planetary abundances, but only for refractory elements.

The Mid-Infrared instrument (MIRI) on board the James Webb Space Telescope will perform the first ever characterization of young giant exoplanets observed by direct imaging in the 5-28 microns spectral range.

Moons are suspected to influence rocky exoplanet habitability, and gaseous exoplanets in stellar habitable zones could harbour abundant and diverse moons to target in the search for extraterrestrial habitats.